Power press



J. NELsoN POWER PRESS 2 Sheets-Shoot 1 Filed Jan. 16. 1922 .my 29. m4.. 1,503,131

J. NELSON POWER PRESS Filed Jan. 16. 1982 2 Shouts-Sheet 2 MMM.

Patented Julyze, 1924.

uNiTl-:D lsfrA'rus PATENT OFFICE..

JOHN NELSON, OF CHICAGO, ILLINOIS, ASSIONOR TO MARQUETTE TOOL & MANU- FACTUBJNG COIIHPANY, OF CHICAGO, ILLINOIS,` A CORPORATION OF ILLINOIS.

i POWER ranss.

Application filed January 16, 19252.V Serial No. 529,494.

To all` whom it mayroacen:

' Beit known that I, JOHN NELSON, a' citizen of the United States of America, and

a resident of Chicago,- county of Cook, and

means forregulating the pressure of the die Y cushions so as to control the gripping action of the movable die and draw ring upon U the drawmg Operatlon. The present -mventhe metal blank; to provide means for automatically varying such pressure and gri ping action during the down stroke of t e die; to provide improved means for relieving the pressure in the apparatus during Vthe return stroke of vthe die so as to avoid .the objectionable back-kick or premature rise of the pressure pad which occurs in some presses upon the up-stroke of the forming die; to provide a die cushioning apparatus in which the pressure pad and draw ring are restored to normal position by use of air pressure rather than the usual gravity return found in many presses; to provide improved means for automatically shutting off the su ply of air pressure in case the liquid is rained from the system by the bursting of some part in the apparatus; and

to provide a die cushioning apparatus` for A40 power presses which will minimize the strain upon the dies and draw ring and upon the metal being formed.,

An illustrative embodiment of this invention is shown in the accompanying drawings, wherein- Figure 1 is an elevation, partly in vertical lsection, showing a die cushlomng apparatus for power presses constructed in accordance withthis invention.

Figure 2 is an enlarged vertical section of the adjustable flow regulator.

Figure 3 is a plan of the battery of cylinders, showing the pistons in section.

Figure 4 is an enlarged detail, partly in section, showing part of the automatic control means for the adjustable flow regulator.

Figure 5 is an enlarged detail showing the connections between the power shaft and certain of the valves.

The construction here illustrated includes the usual type of power press having a pair of interacting dies, one of which is movable toward the other for drawing out the desired articles in one operation or by successive operations. The periphery of the blank operated upon is gripped between the draw ring and the movable die during the forming operation. In some operations of the press it is essential that the periphery of the blank be ysecured positively against movement, while for other operations it is desirable to have the blank yield suticiently to permit it to be drawn inwardly during tion relates particularly to means for varying this gripping action on the periphery of the article so as to either permit or restrain motion thereof exactly as desired in the dii'erent classes of work in which the press may be employed. The purposes of this invention are accomplished by utilizing in one apparatus both compressed air and a liquid resistance controllable by flow regulators and automatically operated valves whereby the positiveresistance of a liquid only may be utilized, or with this resistance may be combined the resilient action of compressed air.

In the form shown, the die cushioning apparatus is applied to a single acting power press comprising a frame 1, which Includes vertical guides 2, and a horizontally ldisposed bolster plate 3, on which is mounted a stationary die 4, which coacts with a movable die 5 carried in the upper part of the frame and actuated by a power shaft 6. A' blank holder or draw ring 7 is arranged between the interacting dies lfor supporting tlie metal blank during the forming operation. Suspended from the bolster plate 3 by rods 8, is a supporting plate 9J which supports part of the cushioning apparatus.

In the form shown, the cushioning apparatus includes a battery of cylinders 10 and a pressure tank 11 connected by a reservoir or connection 12 which provides for a liquid column movable under the action of the forming die against. the yielding resistance of the air or other gas stored under pressure in the tank 11.

The cylinders are rigidly secured to the supporting plate 9 in an inverted position and are provided with pistons 13 extending through the upper ends of the cylinders and supporting a pressure pad 14 arranged below the bolster plate. Carried by the pressure pad 14 and extending through apertures in the bolster plate are a plurality of pins 15, which support the draw ring 7 on their upper ends. The arrangement of the draw ring and pressure pad permits the impact of the movable die 5 upon the draw ring to be imparted through the pistons 13 to the liquid column which is moved against the yielding resistance of the air or other gas in the tank 11.

The air tank 11 comprises the usual form of pressure tank having an inlet 16 connected to the source of air supply (not shown) and an outlet 17 leading to the reservoir or connection 12. Mounted in the inlet 16, is a regulating valve 18 by which the air supply is regulated so as to maintain the desired normal pressure within the tank. An air pressure gauge 19 is mounted on top of the tank adjacent to the inlet. Arranged on one side of the tank, is a gauge glass 20 for measuring the level of the liquid column to determine the quantity of air in the tank. The proper quantity and pressure of the air within the tank 11 which will produce the most satisfactory results for the different operations of the press are determined by experiment and, when once determined, the desired conditions may readily be produced wheneverlrequired. The top of the liquid column serves Vas a piston head which coacts with the compressed air in the tank 11 which yieldingly 4resists the movement of the liquid through the reservoir or connection 12 under the action of the pistons 13.

The reservoir or connection 12l includes a main supply tube 21 communicating at one end with the tank 11 and at the other end being connected to branch tubes 22, which extend upwardly through apertures in the supporting platt 9, in communication with the cylinders 10. Located in the supply tube 12 adjacent to the tank 11, is a float valve 23 normally held open by the liquid column and arranged to close communication between the air supply and the reservoir 12 when the liquid falls below the float valve, as in cases of accidenttwlien the liquid is drained from the system through the bursting of some part of the connection 12.

The control means for regulating the flow of the liquid column under the action of the pistons 13 comprises a system of check valves and flow regulators or resistance valves, arranged to permit the flow of liquid to the cylinders 10 under the action ofthe gas in the tank 11 and to resist the return flow under the action of the pistons 13.

The control means includes a flow regulator 24 in the form of a hand operated valve arranged in the main supply tube. The valve 24 is normally closed and is adjusted so as to be automatically opened only when the liquid column is subjected to the maximum amount of pressure which is imparted to the draw ring by the movable die 5. Extending around the Valve 24 is a pair of by-passes 25 and 26. In the by-pass 25 is located a check valve 27 arranged to permit the liquid column to move toward the cylinders 10 for restoring the pistons 13 to normal position under the action of the gas in the tank 11.

In the by-pass 26 is located a flow regulator in the form of a valve 28 which is arranged to permit the adjustment of the ret sistance to the action of the pistons 13. The valve 28 has a handle 29 to permit hand control of the resistance and is also provided with means for automatic operation so as to obtain a variable resistance during the forming stroke of the movable die 5. The automatic Ameans for controlling the regulator 28 includes a gear 30 fixed on the valve stem and meshing With the rack 31 arranged for operation by the power shaft 6. The valve 28 is normally urged toits closed position by a spring 32. The rack 31 comprises a pair of spaced members 33 connected at their ends and slotted to receive removable teeth 34, which may be inserted on either side of the rack for engagement with the gear 30 at either side thereof. In some classes of work it is desirable to increase the pressure of the die and draw a ring upon the metal shell during the forming stroke of the die, while in other cases it is desirable .to decrease such resistance during the forming operation. If it is desired to adjust the valve 28 so as to increase the resistance during the down stroke of the die 5, the teeth 34 are arranged on one side of the rack, and if it is desired to decrease the resistance during the down stroke of the die 5, the teeth 34 are arranged on the opposite side of the rack. The rack 33 is carried by a rod- 35, the upper end of which has a strap 36 which passes around an eccentric 37 fixed on one end of the powershaft 6. By the co- 'action of the eccentric 37 and strap 36.tl1e

rod 35 is reciprocated to adjust the valve 28 during each rotation of the power shaft.

To avoid the objectionable back-kick lor premature rise of the pressure pad 14 which occurs in some presses upon the lip-stroke of the forming die,lthe apparatus includesrelieving means for reduclng the pressure of the liquid in the connection 12. The relieving means comprises a shut-off valve 38 and a relief pump 39 arranged in the reservoir Vnected to a rod 41 which is normally .urged upwardlyto close the valve by a sprmg 42 connected at one end to the rod and at the other end to a bracket 43 mounted on the press frame 1. j The upper end of the rod 41 -carries a roller-44 (Fig. 5) which coacts with at snail-cam 45 fixed-on the power shaft 6 so as tonormally force the rod 41 downwardly against the action of the spring 42 for holding the valve 38 open. V The snail cam 45 is' adjusted with respect to the power shaft 6 so that the high point of the cam will pass the` roller 44 at the time the die 5 reaches the limit of its down stroke, thereby permitting the spring 42 to urge the rod 41 upwardly to close the valve 38, for a brief period during the up stroke of the die 5; The closing of the valve 38 for a' brief period during the up stroke of the v die 5 prevents the liquid column, under the actionof the'compressed air, from forcin the pistons 13 upwardly until the die 5 reac es a certain point in its up stroke. .g

I he relief pump 39 comprises a-cylinder 46 communicating with the main supply tube 21 and apiston 47. The piston 47 is connected to a bracket 48 carried by the forming die 5, so that during the. up stroke of the die 5, the piston 47 isdrawn upwardly to 'reduce the pressure of the liquid within the" supply tube.

I n the operation of forming some classes of work, it is often desirable that certain parts of the periphery of the metalblank be subjected Yto more pressure tha-n other parts tentl than certain other portions. This variofthe periphery -during the same operation s o 'as to permit portions of the metal to be drawn inwardly by the die to a greater exation in pressure is accomplishedqby a system of check valves and flow regulators arranged to adjust the resistance of-ea'c'h of the cylinders 10V independently of the others: Each of thebranch passages 22 (Fig. 3)

contains a iiow regulator 49 in the form of a hand operated valve similar in construction to valve 24. If desired, the valves 49 may be adjustable and automatically operated similar to the valve 28. Extending around each of the flow regulators 49, is a by-pass 50 containing a check valve 51 similar in construction to check valve 27.

In operation, the metal blank is placed on the draw ring 7 so that upon the down stroke of the die 5 the metal shell is pressed down over the stationary die 4. During the forming operation, the periphery of the metal blank is gripped between the draw ring 7 and the movable die 5. In some operations it is essential that this gripping action be suflicient to positively secure the periphery of theV blank against inward creepingj while for other operations it is door proper. In forming the belly of the door shell it is essential that the periphery of the metal blank be firmly gripped between the draw ring and die 5 so as to secure the blank against creeping. vIn the second operation of forming the door shell it is` desirable 'to permit the metalto creep in wardly under the action of the die and therefore the periphery of the blank is held with less pressure between the forming die 5 and the draw ring 7. When it is desired to secure the metal blankagainst creeping, the valve 28 is disconnected -from the power shaft 6 and all of the flow regulators in the system' are adjusted for the maximum pressure; that is, a pressure which will firmly grip the periphery of the metal blank between the draw' ring 7 and die 5. Upon the down stroke of the-forming die, theflow regulators open under the pressureof the pistons 13 on the liquid column. Upon the up stroke ofy the die 5 the flow regulators automatically close and the liquid column flows back through the check valves under the action of the compressed air, as soon as the valve 38 is opened by the up-stroke of the die 5. When'it is desired to permit the metal blank to yield inwardly, the valve 28 is adjusted so as to decrease the resistance to the liquid column, thereby decreasing the pressure of the draw ring and die 5 upon the periphery of the metal blank. If it is desired to exert more pressure on certain parts of theperiphery" of the metal shell than on other portions of the periphery, the valves .49 are adjusted "so as to open under the desired ressures.

In some c asses of work it is desirable to vary the pressure of the'draw ring 7 and die 5 upon the periphery of the metal blank during the forming stroke of the die. To obtain such variable pressure or gripping action, the rack 33 is arranged to coact with the gear 30 so as to adjust the resistance of the valve 28 to the liquid column during the this invention has been herein shown and described, it will be understood that numerous details of the `construction may be altered or omitted without departing from the spirit of this invention as vdefined by the following claims. Y Y* I claim:

1. In a die press,the combination of a,v fluid pressurecontrol system including a pressure pad, a controlling valve, means for causing a iuid pressure to be exerted upon said pad, and meansfor automatically increasing said pressure during the movementof said pad.

2. In a die press, the combination of a uid pressure control system including a. pressure pad, a controlling valve, means for causing a fluid pressure to be exerted upon said pad, and means for automatically decreasing said pressure during the movement of the said pad.

3. In a die press, the combination of pistons and cylinders, a pressure pad, iuid pressure means including automatically operating controlling valves therefor, and means for relieving said fluid pressure during the cycle of operation of the pad.

4. In a die press, the combination of pistons and cylinders,\ a pressure pad, fluid pressure means including automatically operating controlling valves therefor, and means for relieving said fluid pressure during the cycle of operation of the pad and at a predetermined point in the operation of the pressure pad.

5. The combination with a power press including a power shaft and a pair of interacting dies, of a die cushioning apparatus comprising cylinder and piston members, one of said members being adapted for supporting a blank holder,` a reservoir communicating with said cylinder and providing for a Huid column movable under the action of said one member, and automatically operating relieving means in said reservoir for relieving the Huid pressure during the return stroke of said one member.

6. The combination with a power press including a powershaft and a pair of interacting dies, of adie cushioning apparatus comprising cylinder and piston members, one of said members being adapted for supporting a blank holder, a chamber for containing gas under pressure, a connection between said cylinder and chamber providing for a liquid column movable under the action of said one member against the yielding resistance of the gas in said chamber,

and relieving means in said connection and controllable by said power shaft for relieving the pressure of the liquid in said connection during the return stroke of said one member.

7. The combination with a power press including a power shaft and a pair of interacting dies, of a die cushioning apparatus comprising cylinder and piston members, one of said members being adapted for supporting a blank holder, a chamber for containing gas under pressure, a connection between said cylinder and chamber providing for a liquid column movable under the action of said one member against the yielding resistance of the gas in said chamber, a

valve in said connection for shutting 0H the return flow-of liquid to said cylinder ander the action of the gas in said chamber, and means operating automatically to close said valve when said die reaches a predetermined point in its cycle of operation.

8. The combination with a power press including a power shaft and a pair of interacting dies, of a die cushioning apparatus comprising cylinder and piston members, one of said members being adapted for supporting a blank holder, a chamber for oontaining gas under pressure, a connection between said cylinder and chamber providing for a liquid column movable under the action of said one member against the yielding resistance of the gas in said chamber, and a relief pump arranged in said connection and controllable by the power shaft for relieving the pressure of the liquid in said connection during the back stroke of said one member.

9. The combination with a power press including a power shaft and a pair of interacting dies, of a die cushioning apparatus comprising cylinder and piston members, one of said members being adapted for supporting a blank holder, a chamber for containing gas under pressure, a connection between said cylinder and chamber providing' for a liquid column movable under the action of said one member against the yielding resistance of the gas in said chamber, a va'lvein said connection for controlling the flow of liquid through said connection to resist the action of said one member, means for regulating lsaid valve, said means being controllable by the power shaft for varying said resistance during the movement of one of said dies, and relieving means in said connection between said valve and cylinder, said relieving means being controllable by the power shaft for relieving the pressure yof the liquid in said connection during the return stroke of said one member.

l0. A die cushioning apparatus for power pressesl comprising cylinder and piston members, one of which is adapted for supporting a blank holder, a chamber for containing gas under pressure, a -connection between said cylinder and chamber providing for a liquid column movable under the action of said one member against the yielding resistance-of the gas in said chamber, and means for automatically closing communication between said chamber and connection when the liquid in said connection falls below a prevcycle of operation of the dies.

12. The combination with a power press v'including a power shaft and a pair of intercushioningv apparatusl acting dies, of a die comprising cylinder and piston members,

one of saidmembers being adapted for supportingaL-b ank holder, a chamber for containing \gas under pressure, a connec'tlon between said cylinder and chamber providing for a liquid column movable under the action of said one member against the ielding resistance of the gas in' said chamer, a check valve in said connection arranged to permit the liquid to low toward said cylinder underthe' action of the gas in said chamber, a" by- `ass around said; check valve, a valve in sai by-pass arranged to control the low of liquid toward said chamber vto resist the action ofl saidY lone member, meansforregulating said resistance valve, 'said means being controllable by the power shaft for varying said resistance during themovementof one of said dies,

- and relieving meansjin said connection betweensaid resistance valve and cylinder, said relieving means being controllable by the power shaft for relieving the pressure of theV liquid in said connection during the return stroke of said one member.

13. A powerpress comprising a supporting frame', a bolster plate mounted on said frame and supporting a stationary die, a power shaft, a movablel die, a cylinder and piston mounted below said bolster plate, a

pressure pad supported on said piston, a draw ring located between sald dies and supported on said pressure pad by pins extending through said bolster plate, a tank for containing gas under pressure, a connection between said cylinder and tank providing for a liquid column movable under the action of sald piston against the yielding resistance of the gas in said chamber, a check valve in said connection arranged to permit the liquid to flow toward said cylinder, a by-pass around said check valve, a

.valve in said by-pass arranged to control the liow of liquid toward said tank to resist the action of said piston, a gear for regulating said resistance valve, a rack arranged to mesh with said gear and controllable by the power shaft for regulating said resistance valve during the stroke of said mov-I able die, relieving means in said connection between said resistance valve4 and piston, saidV relieving means being controlled by the power shaft for -relieving the pressure of the liquid in said connection during the return stroke of said piston, and a {ioat valve in said connection arranged to close communication betweensaid connection and gas tank when the liquid in said connection falls of said one member, the said relieving meansl including mechanism adapted to beset for. relieving the fluid pressure `at a predetermined point in the cycle of operation yofthe press during the forming operation.

Signed at Chicago this 12 day of Jan., 1922. i

lIOHN NELSON. 

